1. Field of the Invention
The present invention relates to a dental treating apparatus with a hand piece, more specifically, to a dental treating apparatus that causes a cutting tool for cutting and enlarging an inner wall of a root canal of a tooth to be driven.
2. Description of the Background Art
As for a dental treating apparatus with a hand piece, there is, for example, an apparatus for providing treatment by attaching a cutting tool to a head unit of a hand piece and driving the cutting tool to cut and enlarge a root canal of a tooth. U.S. Pat. No. 3,264,607 (PTL 1), U.S. Pat. No. 3,676,753 (PTL 2) and U.S. Pat. No. 3,615,209 (PTL 3) disclose various types of driving control in order to, for example, prevent breakage due to a load applied to the cutting tool when the dental treating apparatus causes the cutting tool to be driven to cut and enlarge the root canal of the tooth.
A dental treating apparatus disclosed in PTL 1 includes detecting means for detecting a load applied to a cutting tool, and control means for reversely rotating a cutting tool driving motor when the detected load reaches a preset reference.
A dental treating apparatus disclosed in PTL 2 includes driving means for driving a cutting tool, load detecting means for detecting a load applied to the cutting tool, root canal length measuring means for measuring a root canal length by using the cutting tool, reference load setting means for arbitrarily presetting a reference load, and control means for controlling the driving means. When the load detected by the load detecting means exceeds the reference load, the control means controls the driving means by any one of the operations of stopping driving of the cutting tool, reducing an amount of driving, reversing rotation, and repeating normal rotation and reverse rotation, such that the load applied to the cutting tool is reduced. Furthermore, based on a value of the root canal length measured by the root canal length measuring means, the control means controls the driving means such that the amount of driving the cutting tool becomes smaller as a distance from the cutting tool to a root apex becomes shorter.
A dental treating apparatus disclosed in PTL 3 includes driving means for driving a cutting tool, root canal length measuring means for measuring a root canal length, and control means for controlling the driving means such that the driving force of the cutting tool changes in accordance with a value of the root canal length measured by the root canal length measuring means. The control means includes number-of-rotations control means for controlling the number of rotations of the cutting tool. Based on the value of the root canal length measured by the root canal length measuring means, the number-of-rotations control means controls the driving means such that the number of rotations of the cutting tool becomes smaller as a distance from the cutting tool to a root apex becomes shorter.
The cutting tool used for the dental treating apparatus is broadly divided into a clockwise-rotating cutting tool having a blade formed such that the cutting tool can be rotated clockwise as directed toward a tip end to cut an object to be cut, and a counterclockwise-rotating cutting tool having a blade formed such that the cutting tool can be rotated counterclockwise as directed toward the tip end to cut the object to be cut.
The cutting tool is, however, in the shape of a needle having a length of approximately several tens of millimeters, and at first glance of the shape of the blade formed on a surface, it is difficult for a user to distinguish between the clockwise-rotating cutting tool and the counterclockwise-rotating cutting tool.
The clockwise-rotating cutting tool and the counterclockwise-rotating cutting tool can be both held on the head unit of the hand piece. Therefore, in a clinical scene where the dental treating apparatus is used, the clockwise-rotating cutting tool may be used or the counterclockwise-rotating cutting tool may be used, and thus, the user must identify whether the cutting tool held on the head unit of the hand piece is the clockwise-rotating cutting tool or the counterclockwise-rotating cutting tool. Unless the user drives the cutting tool at a rotation appropriate for the cutting tool held on the head unit, the user cannot properly cut the root canal of the tooth.
Furthermore, when various types of driving control disclosed in PTLs 1 to 3 are performed in the dental treating apparatus, false driving control is performed and treatment cannot be provided safely unless the user checks whether the driving control is driving control appropriate for the clockwise-rotating cutting tool or driving control appropriate for the counterclockwise-rotating cutting tool.